Automatic tracer valve

ABSTRACT

An automatic tracer valve having three mutually perpendicular control axes with a four-way spool valve on each of them. The spool of the first of the spool valves mounts a stylus for axial movement with the spool and for lateral tilting movement in all directions relative to the respective axis. An operator sleeve surrounds the stylus and has a bias bore in which there is a ball that makes a sliding and rolling fluid-sealing fit therein and bears against the side of the stylus to exert a bias force against it causing the stylus to tilt. This force is adjustable by varying the pneumatic pressure on the ball. A second bias bore is aligned with the axis of the first valve and also includes a ball which makes a sliding fit therein. This ball tends to bias the first spool in one direction, and again the force is regulable as a function of pneumatic pressure. Means is provided for sensing deflection of the stylus so as to maintain it tilted in a desired direction, this means comprising a reaction surface whose lateral position is responsive to tilting of the stylus and a sensing port discharging air under pressure against the same so as to form a variable orifice whose position indicates the amount and direction of deflection of the stylus. The other two spools are yoked to the stylus so as to be moved along their respective axes in response to its tilting.

United States Patent [72] Inventor Henry E. Rombeck Valinda. Calif.

21 Appl N0. 854

[22] Filed Jan. 6, I970 [45] Patented Nov. 16, 1971 [73] Assignee Textron lnc.

Covina, Calif.

[54] AUTOMATIC TRACER VALVE 10 Claims, 4 Drawing Figs.

[52] US. Cl 251/3, 90/62 [51] lnt.Cl B23q35/l6 [50] Field of Search 90/62; 60/97 T; 251/3 [56] References Cited UNITED STATES PATENTS 2,835,466 5/1958 Rosebrook 251/3 2,909,357 10/1959 Rosebrook 251/3 3,459.402 8/1969 Weaver..... 251/3 3,529,801 9/1970 Negoro 251/3 4 WAY PEX i/05 i/M Primary Examiner-M. Cary Nelson Assistant Llraminer- Richard Gerard Auorney-Angus & Mon

ABSTRACT: An automatic tracer valve having three mutually perpendicular control axes with a four-way spool valve on each of them. The spool of the first of the spool valves mounts a stylus for axial movement with the spool and for lateral tilting movement in all directions relative to the respective axis. An operator sleeve surrounds the stylus and has a bias bore in which there is a ball that makes a sliding and rolling fluid-sealing fit therein and bears against the side of the stylus to exert a bias force against it causing the stylus to tilt. This force is ad jUSlflblC by varying the pneumatic pressure on the ball. A second bias bore is aligned with the axis of the first valve and also includes a ball which makes a sliding fit therein This ball tends to bias the first spool in one direction. and again the force is regulable as a function of pneumatic pressure. Means is provided for sensing deflection of the stylus so as to maintain it tilted in a desired direction. this means comprising a reaction surface whose lateral position is responsive to tilting of the stylus and a sensing port discharging air under pressure against the same so as to form a variable orifice whose position indicates the amount and direction of deflection of the stylus. The other two spools are yoked to the stylus so as to be moved along their respective axes in response to its tilting.

' INVENTOR. HENRY E. ROMBECK ATTORNEY):

SHEET 2 BF 3 PATENTEDuov 1s nan MS \Q Q% s PATENTEDunv 16 I971 SHEET 3 BF 3 INVENTOR. HENRY E. ROMBECK ATTOR/YEYJ.

AUTOMATIC TRACER VALVE This invention relates to an automatic three-dimension tracer valve and includes means improving its operation such as by providing bias means for the stylus which do not impede its up and down motion and which have a conveniently variable bias force applicable thereto, and also a fluid bias applied to a vertical spool valve, the bias of which is similarly ad justable and substantially friction free. Both said bias means have the further advantage that they act as springs without a constant so that the forces they exert are not a function of deflection.

The invention will be fully understood from the following detailed description and the accompanying drawings, in which:

FIGS. 1 and 1A are axial cross sections of the presently preferred embodiment of the invention, FIG. 1A joining directly to the top of FIG. 1 and continuing the same drawing;

FIG. 2 is a schematic illustration of the force and control system included in the invention; and

FIG. 3 is a schematic cross section taken at line 3-3 of FIG. I.

The automatic tracer valve includes a body ll which is adapted by any desirable means to be attached to a machine tool which it is to control. A milling machine is the most frequently encountered application of this class of tracer valve. An illustrative example of the use of an automatic valve of this general class is shown in Rosebrook, U.S. Pat. No. 2,909,357, issued Oct. 20, 1959. This invention comprises an improvement on that valve.

The body includes a nose 12 at the lower end and defines a first, second and third axis l3, l4, and 15, respectively. First axis 13 is generally vertically oriented. First, second and third spool valves l6, l7 and 18, extend along respective first, second and third axes. Only spool valve 16 will be described in detail, the others being substantially the same. These are the same class of tracer valves as are disclosed in the aforesaid Rosebrook patent and also in Rosebrook, U.S. Pat. No. 2,753,l45, issued July 3, 1956. A characteristic feature of such valves is a sleeve 20 which has a pair of motor grooves 21, 22, connected by conduitry (not shown) to the two operating ports of a reversible motor or other motor means to operate a machine tool slide. A spool 23 makes a sliding fluidsealing fit inside a cylindrical spool passage 24 and this spool includes a central pressure groove 25 and a pair of exhaust grooves 26, 27. The wall of the sleeve is pierced by conduitry (not shown) that is connected to a source of hydraulic fluid under pressure and the exhaust grooves are connected to a reservoir. This is a common class of valve and includes no details which are of especial importance to this invention.

Stylus has a central axis 31 which is nominally parallel to first axis 13. It has a first ball-like member 32 which bears against a seat 33 inside spool 23 of the first spool valve. A retainer 34 traps the first ball-like member in the position shown and is held in place by a cap 35 which is threaded to the spool. Therefore, the stylus is universally laterally tiltable around the center of ball-like member 32 and is axially shiftable with the first spool. Cap 35 includes a rate control shoulder 36 for a purpose later to be described.

A yoke 40 surrounds an annular ring 41 carried by the stylus near its upper end which yoke in the manner described in Rosebrook, U.S. Pat. No. 2,835,466, issued May 20, 1958, moves the respective second and third spool valves along their respective axes as components of the stylus own tilting action. The details of this yoke form no part of this invention and all that needs to be remarked here is the function which it produces and the fact that the yoke does not obstruct the movement ofthe stylus along the first axis.

A stylus passage 42 passes through the first spool in order for the stylus to reach the yoke. Similarly the stylus projects below the first ball-like member 32 and passes through a stylus passage 43 in an operator sleeve 45. This sleeve is supported in the nose of the body by a pair of bearings 46, 47, the bearings being held in place by a snapring 48 at the bottom and by a retainer 49 at the top. It will thereby be seen that the operator sleeve is free to rotate in the body.

A sensing air inlet port 50 passes through the wall of the operator sleeve and terminates at an external groove 51 which is connected by conduitry (not shown) to a source of sensing pneumatic pressure. Air inlet port 50 proceeds through an air passage 52 to a sensing orifice 53, discharging into the stylus passage 43. A vent groove 54 is similarly formed around the outside of the operator sleeve and is communicated with by a bleed port 55 so as to isolate the groove 51 from a bias groove 56. Bias groove 56 extends peripherally around the operator sleeve and is connected by means (not shown) to a pneumatic circuit yet to be described.

A bias bore 57 is circularly cylindrical and extends normally to the first axis. Within it there fits a first bias ball 58 which makes a sliding fluid-sealing fit with the wall of bore 57. It is also rotatable therein. As can be seen in FIG. I, this ball can be brought to bear against the wall of the stylus in a cylindrical region 59 by pneumatic pressure exerted in bias groove 56. The magnitude of the force is a function of the cross-sectional area of the ball and of the pressure in this groove. It will be noted that when the stylus moves up and down the ball simply rotates and creates no frictional restraint on the stylus. Similarly, it behaves as a spring without a constant so that regardless of the amount of deflection, the stylus faces a constant force. FIG. 1 is simplified to show a one ball opposed in direction to the sensing orifice. This arrangement is suitable, but FIG. 3 shows the preferred embodiment which includes two first bias balls disposed apiece with the bisector of the 90 angle aligned with and opposed to the sensing orifice 53. There is greater stability in such an arrangement.

Miscellaneous seals are provided'in the outer wall of the operator sleeve to seal between the various pneumatic areas and isolate them from each other.

At the bottom of the nose there is a guide plate 65 which includes a pair of guide surfaces 66, 67 on opposite sides thereof. The planes of these surfaces are normal to the first axis. A slide member 68 includes a pair of opposed surfaces 69, 70. The surfaces are on members which are held together by screws 72, and which abut before exerting too strong a clamping force on the guide surfaces so that the slide member is able to slide laterally in a plane normal to the first axis. It is caused to slide by the embracing contact of the wall 73 of a bore in the slide member against another ball-like member 74.

A reaction surface 75 is a surface of revolution and preferably conical, which is formed on the slide member and extends up into the region where it will be opposed by the sensing port. The region between the reaction surface and the exit of the sensing port is a variable orifice whose condition will determine the operation of means to cause the automatic operation of the device. It will now be seen that when the stylus tilts it will cause the slide member to slide back and forth in its plane, moving the reaction surface in such amanner relative to the sensing port as to change the effective area of the orifice and provide a signal. This is entirely in accordance with the design and technique of operation of the device shown in Rosebrook U.S. Pat. No. 2,909,357.

Guide plate 65 is mounted to the body in such a manner that it can be moved along the first axis so as to vary the amount of permissible deflection of the stylus. For this purpose, sleeve has internal threads 121 which are engaged to an external thread 122 on body 12. A telescopic cover 123 surrounds the junction of the sleeve and the body, and a setscrew 124 holds the cover in place. Screws 125 mount the guide plate to the lower end of the sleeve, Turning the sleeve moves the guide plate up or down along axis 13, and varies the spacing between surface 75 and surface 126 on operator sleeve 45. The smaller this clearance, the smaller can be the deflection of the stylus. and conversely, the greater the clearance, the greater can be the deflection.

A second bias bore 80 is formed in the end of the first sleeve, which sleeve constitutes structure fixed to the body. Its bore is parallel to the first axis and encloses a second bias ball 81 which bears against an upper flange 82 on retainer 34. There may be two or more of these bias bores spaced angularly apart around axis 13 for balance if desired. It will be noted that pressure in the bias bore on the upper side of the ball will cause the retainer and thereby the first spool to be forced downwardly and to take the stylus with it. There is a downward limit defined by the vertically adjustable location of a second rate control shoulder 83 which is adapted to be home against by shoulder 36 after a sufficient axial movement occurs. Contact of the shoulders constitutes the limiting control over plunging movement of a cutting tool. At null and other positions, there will be a spacing 84 between these shoulders. The maximum attainable spacing 84 (and also the maximum plunging rate) may be adjustably selected by turning knob 85 around axis 13. A sloped slot 86 is provided in which this knob can move. This knob has a stem 87 which is threaded into a threaded ring 88 which ring has an external thread 89 threaded into an internal thread 90 mounted to structure fixed to the body. An internal ring 91 carries the second rate control shoulder 83, this ring being threaded to ring 88. A set screw 92 holds these two rings in their adjusted condition. It will thereby be seen that moving knob 85 will cause shoulder 83 to move up or down thereby determining the maximum downward displacement of the first axis spool.

The yoke causes conventional motions in the second and third spool valves as set forth fully in Rosebrook, US. Pat. No. 2,853,466.

FIG. 2 shows the hydraulic control systems utilized herein, in a schematically rearranged representation. The first and second bias balls will clearly be seen in their thrusting condition together with regulators I and 101 to regulate and adjust the pressures on them. Off-on valves 102, 103 are provided in these circuits. Another regulator 104 provides steering air past a check valve 105 to the air-sensing orifice 53 from which it is conducted to a pressure-sensitive sensor 106 which controls the position of a four-way valve 107 that determines the direction of feed of pressurized hydraulic fluid to a bidirectional motor 108 which is coupled to the operator sleeve. Rotation of the-operator sleeve will occur by driving belt 109 with motor 108 in the manner of the aforesaid Rosebrook US. Pat. No. 2,909,357 patent in an attempt to restore the stylus to the condition representing a constant angle relative to the template. Rotation of this sleeve will, of course, adjust the direction of application of bias by the first bias ball.

The operation of the device is completely conventional in accordance with the aforesaid Rosebrook patent, but has the considerable advantage of adjustable bias forces without frictional effects, and also without spring constants. It has the further advantage of ad justability of bias forces from a remote location by setting the regulators. In addition, the sensing orifice is freed from angular errors because of the lateral sliding motion of the slide member. Accordingly, this invention constitutes a substantial improvement in an already proved automatic valve.

lclaim:

1. In an automatic tracer valve having a first, second, and third mutually perpendicular control axis, and a first, second, and third four-way spool valve including a spool and a sleeve axially aligned on the respective first, second and third axes, said spool valves each having a central null condition occurring at a centralized position of the spool in the sleeve in which no net fluid flow is passed therethrough, and two off-null operational positions in which the spool is axially displaced in one direction or the other from null so as to permit a net flow in one direction or in an opposite direction for the control of machine tool motive means as a function of the amount of spool displacement from the null condition in a respective sleeve, and a body mounting said spool valves and adapted to be mounted to a machine tool frame, the improvement comprising: a stylus having a longitudinal axis nominally aligned with the first axis and passing through the spool of the first valve; a first ball-like member on the stylus; mounting means attached to the spool of the first spool valve pivotally mounting the stylus to said spool for universal tilting movement relative to the first axis and for axial movement along the first axis with said spool; a guide plate having guide surfaces normal to and extending toward said first axis; a slide member mounted to said guide plate and engaged to said guide surfaces so as to move exclusively in a plane normal to the first axis; a reaction surface carried by said slide member facing away from said first axis, said reaction surface being a surface of revolution with an axis parallel to the first axis. said slide member having an axial cylindrical passage therein; a second ball-like member on said stylus inside of and embraced by the wall of the cylindrical passage and spaced from the first ball-like member so as to move the slide member in its plane when the stylus is angularly tilted; a rotatable operator sleeve having a central passage whose wall surrounds the stylus between the two balllike members, the operator sleeve having a sensing port opening into the central passage adjacent to the reaction surface so as to create a variable sensing orifice between them, the operator sleeve rotating around said first axis and having a first bias bore extending normal to the first axis; a first bias ball making a rolling and sliding fluid-sealing fit in said bias bore and bearing against the stylus in response to pneumatic pressure exerted against its side away from the stylus; a second bias bore in structure fixed to the body and extending parallel to the first axis; a second bias ball making a sliding fluid-sealing fit in said second bias bore and bearing against structure fixed to the first spool to force the first spool toward the guide plate in response to pneumatic pressure exerted against the second bias ball from its side away from said structure; pneumatic circuitry including adjustable pressure regulator valves conducting air at an adjusted regulated pressure to the first and second bias bores and to the sensing port; reversible drive means for rotating the operator sleeve in response to the pressure condition of the sensing orifice; rate control means adjustably limiting the distance the first spool can be moved by the second bias ball; and yoke means mounting the second and third spool valves to the stylus so as to move in their respective axes in response to tilting of the stylus, but independently of axial movement of the stylus.

2. An automatic tracer valve according to claim I in which the guide plate has a pair of parallel, opposed planar surfaces as said guide surfaces, and in which said slide member includes a pair of spaced'apart surfaces each of which bears against one of said planar surfaces.

3. An automatic tracer valve according to claim 1 in which said rate control means includes a reference thread formed in the body surrounding and facing toward the stylus, an externally threaded ring engaged to the reference thread and movable along the first axis by rotation thereof, and a shoulder on said ring adapted to be abutted by structure fixed to the first spool to limit the movement of the first spool.

4. An automatic tracer valve according to claim 3 in which the guide plate has a pair of parallel, opposed planar surfaces as said guide surfaces, and in which said slide member includes a pair of spaced-apart surfaces each of which bears against one of said planar surfaces.

5. An automatic tracer valve according to claim I in which the reaction surface is conical.

6. An automatic tracer valve according to claim 5 in which the guide plate has a pair of parallel, opposed planar surfaces as said guide surfaces, and in which said slide member includes a pair of spaced-apart surfaces each of which bears against one of said planar surfaces.

7. An automatic tracer valve according to claim 5 in which said rate control means includes a reference thread formed in the body surrounding and facing toward the stylus, an externally threaded ring engaged to the reference thread and mova' ble along the first axis by rotation thereof, and a shoulder on said ring adapted to be abutted by structure fixed to the first spool to limit the movement of the first spool.

8. An automatic tracer valve according to claim 7 in which the guide plate has a pair of parallel, opposed planar surfaces as said guide surfaces, and in which said slide member includes a pair of spaced-apart surfaces each of which bears against one of said planar surfaces.

9. An automatic tracer valve according to claim 8 in which mounting means mounts the guide plate to the body in a manner such that the guide plate is movable along the first axis so as to vary the amount of permissible deflection of the stylus.

10. An automatic tracer valve according to claim 1 in which 5 mounting means mounts the guide plate to the body in a manner such that the guide plate is movable along the first axis so as to vary the amount of permissible deflection of the stylus. 

1. In an automatic tracer valve having a first, second, and third mutually perpendicular control axis, and a first, second, and third four-way spool valve including a spool and a sleeve axially aligned on the respective first, second and third axes, said spool valves each having a central null condition occurring at a centralized position of the spool in the sleeve in which no net fluid flow is passed therethrough, and two off-null operational positions in which the spool is axially displaced in one direction or the other from null so as to permit a net flow in one direction or in an opposite direction for the control of machine tool motive means as a function of the amount of spool displacement from the null condition in a respective sleeve, and a body mounting said spool valves and adapted to be mounted to a machine tool frame, the improvement comprising: a stylus having a longitudinal axis nominally aligned with the first axis and passing through the spool of the first valve; a first ball-like member on the stylus; mounting means attached to the spool of the first spool valve pivotally mounting the stylus to said spool for universal tilting movement relative to the first axis and for axial movement along the first axis with said spool; a guide plate having guide surfaces normal to and extending toward said first axis; a slide member mounted to said guide plate and engaged to said guide surfaces so as to move exclusively in a plane normal to the first axis; a reaction surface carried by said slide member facing away from said first axis, said reaction surface being a surface of revolution with an axis parallel to the first axis, said slide member having an axial cylindrical passage therein; a second ball-like member on said stylus inside of and embraced by the wall of the cylindrical passage and spaced from the first ball-like member so as to move the slide member in its plane when the stylus is angularly tilted; a rotatable operator sleeve having a central passage whose wall surrounds the stylus between the two ball-like members, the operator sleeve having a sensing port opening into the central passage adjacent to the reaction surface so as to create a variable sensing orifice between them, the operator sleeve rotating around said first axis aNd having a first bias bore extending normal to the first axis; a first bias ball making a rolling and sliding fluidsealing fit in said bias bore and bearing against the stylus in response to pneumatic pressure exerted against its side away from the stylus; a second bias bore in structure fixed to the body and extending parallel to the first axis; a second bias ball making a sliding fluid-sealing fit in said second bias bore and bearing against structure fixed to the first spool to force the first spool toward the guide plate in response to pneumatic pressure exerted against the second bias ball from its side away from said structure; pneumatic circuitry including adjustable pressure regulator valves conducting air at an adjusted regulated pressure to the first and second bias bores and to the sensing port; reversible drive means for rotating the operator sleeve in response to the pressure condition of the sensing orifice; rate control means adjustably limiting the distance the first spool can be moved by the second bias ball; and yoke means mounting the second and third spool valves to the stylus so as to move in their respective axes in response to tilting of the stylus, but independently of axial movement of the stylus.
 2. An automatic tracer valve according to claim 1 in which the guide plate has a pair of parallel, opposed planar surfaces as said guide surfaces, and in which said slide member includes a pair of spaced-apart surfaces each of which bears against one of said planar surfaces.
 3. An automatic tracer valve according to claim 1 in which said rate control means includes a reference thread formed in the body surrounding and facing toward the stylus, an externally threaded ring engaged to the reference thread and movable along the first axis by rotation thereof, and a shoulder on said ring adapted to be abutted by structure fixed to the first spool to limit the movement of the first spool.
 4. An automatic tracer valve according to claim 3 in which the guide plate has a pair of parallel, opposed planar surfaces as said guide surfaces, and in which said slide member includes a pair of spaced-apart surfaces each of which bears against one of said planar surfaces.
 5. An automatic tracer valve according to claim 1 in which the reaction surface is conical.
 6. An automatic tracer valve according to claim 5 in which the guide plate has a pair of parallel, opposed planar surfaces as said guide surfaces, and in which said slide member includes a pair of spaced-apart surfaces each of which bears against one of said planar surfaces.
 7. An automatic tracer valve according to claim 5 in which said rate control means includes a reference thread formed in the body surrounding and facing toward the stylus, an externally threaded ring engaged to the reference thread and movable along the first axis by rotation thereof, and a shoulder on said ring adapted to be abutted by structure fixed to the first spool to limit the movement of the first spool.
 8. An automatic tracer valve according to claim 7 in which the guide plate has a pair of parallel, opposed planar surfaces as said guide surfaces, and in which said slide member includes a pair of spaced-apart surfaces each of which bears against one of said planar surfaces.
 9. An automatic tracer valve according to claim 8 in which mounting means mounts the guide plate to the body in a manner such that the guide plate is movable along the first axis so as to vary the amount of permissible deflection of the stylus.
 10. An automatic tracer valve according to claim 1 in which mounting means mounts the guide plate to the body in a manner such that the guide plate is movable along the first axis so as to vary the amount of permissible deflection of the stylus. 